(Video Link)
YouTube user JoergSprave makes fancy slingshots. He was challenged by fans to create one that could fire a machete, and the result is something like a crossbow. "What is it good for? Nothing except attracting people's attention on YouTube." That's a perfectly fine reason.
via Geekologie | Maker's Blog
Firing machetes on something that is unreliable with it's aim as a slingshot. Why don't they just throw the knives in the air and run around trying to avoid the falling machetes because that would be just as dangerous, and would actually be funnier.